fixed focus lens

Abstract

The application discloses a fixed-focus lens which comprises, in order from the object side to the image side along the optical axis, a first lens with negative refractive power, a second lens with negative refractive power, a third lens with positive refractive power, a fourth lens with positive refractive power, a fifth lens with negative refractive power, a sixth lens with positive refractive power and a seventh lens with positive refractive power; wherein the effective focal length F1 of the first lens, the effective focal length F2 of the second lens and the effective focal length F3 of the third lens satisfy: 0.60≤(F2+F3) / F1≤1.57.

Description

Technical Field

[0001] This application relates to the field of optical devices, specifically to a fixed-focus lens. Background Technology

[0002] With the increasing popularity of security monitoring equipment, higher requirements have been placed on monitoring equipment. For example, monitoring equipment needs to have greater light transmission and provide all-weather monitoring images.

[0003] However, current imaging lenses on the market have many problems. For example, they have small relative apertures, which leads to poor light transmission and low edge relative illumination; poor infrared confocality and poor infrared imaging performance at night; low resolution and poor image quality; and excessively long optical length and large size. All of these problems limit the application of imaging lenses in the field of security monitoring. Summary of the Invention

[0004] This application provides a fixed-focus lens that can at least partially solve at least one problem or other problems existing in the prior art.

[0005] One aspect of this application provides a fixed-focus lens that, along the optical axis from the object side to the image plane, sequentially includes a first lens with negative optical power, a second lens with negative optical power, a third lens with positive optical power, a fourth lens with positive optical power, a fifth lens with negative optical power, a sixth lens with positive optical power, and a seventh lens with positive optical power; wherein the effective focal length F1 of the first lens, the effective focal length F2 of the second lens, and the effective focal length F3 of the third lens satisfy: 0.60≤(F2+F3) / F1≤1.57.

[0006] According to an exemplary embodiment of this application, the object-side surface of the first lens is concave, and the image-side surface is concave; the object-side surface of the second lens is convex, and the image-side surface is concave; the object-side surface of the third lens is convex, and the image-side surface is convex; the object-side surface of the fourth lens is convex, and the image-side surface is convex; the object-side surface of the fifth lens is concave, and the image-side surface is concave; the object-side surface of the sixth lens is convex, and the image-side surface is convex; and the object-side surface of the seventh lens is convex, and the image-side surface is concave.

[0007] According to an exemplary embodiment of this application, the total optical length (TTL) of a fixed-focus lens and the back focal length (BFL) of the fixed-focus lens satisfy the following condition: 3.79 ≤ TTL / BFL ≤ 4.13.

[0008] According to an exemplary embodiment of this application, the combined focal length F123 of the first to third lenses and the on-axis distance d4567 from the object side of the fourth lens to the image side of the seventh lens satisfy: -1.10≤F123 / d4567≤-0.83.

[0009] According to an exemplary embodiment of this application, the total optical length TTL of the fixed-focus lens and the holographic height H of the fixed-focus lens satisfy: 3.07≤TTL / H≤3.56.

[0010] According to an exemplary embodiment of this application, the effective focal length F4 of the fourth lens and the effective focal length F1 of the first lens satisfy: -1.57≤F4 / F1≤-1.46.

[0011] According to an exemplary embodiment of this application, the combined focal length F56 of the fifth lens and the sixth lens satisfies the following condition with respect to the total effective focal length F of the fixed-focus lens: 9.0 ≤ F56 / F ≤ 22.9.

[0012] According to an exemplary embodiment of this application, the combined focal length F56 of the fifth and sixth lenses and the effective focal length F4 of the fourth lens satisfy: 3.06≤F56 / F4≤9.6.

[0013] According to an exemplary embodiment of this application, the radius of curvature R11 of the object side of the first lens, the radius of curvature R12 of the image side of the first lens, and the effective focal length F1 of the first lens satisfy: 12.78≤(R11+R12) / F1≤48.

[0014] According to an exemplary embodiment of this application, the quadratic curvature coefficient K21 of the object-side surface of the second lens, the quadratic curvature coefficient K22 of the image-side surface of the second lens, and the effective focal length F2 of the second lens satisfy: 0.04mm -1 ≤|(K21+K22) / F2|≤1.20mm -1 .

[0015] According to an exemplary embodiment of this application, the combined focal length F567 of the fifth to seventh lenses and the effective focal length F1 of the first lens satisfy: -2.37≤F567 / F1≤-1.90.

[0016] According to an exemplary embodiment of this application, the effective focal length F7 of the seventh lens and the total effective focal length F of the fixed-focus lens satisfy: 5.35≤F7 / F≤6.45.

[0017] According to an exemplary embodiment of this application, the second curvature coefficient K71 of the object-side surface of the seventh lens, the second curvature coefficient K72 of the image-side surface of the seventh lens, and the effective focal length F7 of the seventh lens satisfy: 2.97mm -1 ≤(K71+K72) / F7≤5.46mm -1 .

[0018] According to an exemplary embodiment of this application, the fixed-focus lens further includes an aperture stop, and the on-axis distance T1S from the first lens to the aperture stop satisfies the following condition with respect to the total optical length TTL of the fixed-focus lens: 0.15≤T1S / TTL≤0.41.

[0019] According to an exemplary embodiment of this application, the fixed-focus lens further includes an aperture stop, wherein the maximum effective half-diameter SD71 of the object-side surface of the seventh lens and the maximum effective half-diameter SD of the aperture stop are... sto Satisfies: 1.06 ≤ SD71 / SD sto ≤1.65.

[0020] This application employs seven lenses. By rationally allocating the optical power of each lens, the fixed-focus lens can achieve at least one of the following beneficial effects: large aperture, miniaturization, low cost, high resolution, infrared confocal focus, and calorific value. Attached Figure Description

[0021] Other features, objects, and advantages of this application will become more apparent from the following detailed description of non-limiting embodiments with reference to the accompanying drawings.

[0022] Figure 1 A schematic diagram of the structure of a fixed-focus lens according to Embodiment 1 of this application is shown;

[0023] Figure 2 A schematic diagram of the structure of a fixed-focus lens according to Embodiment 2 of this application is shown;

[0024] Figure 3 A schematic diagram of the structure of a fixed-focus lens according to Embodiment 3 of this application is shown; and

[0025] Figure 4 A schematic diagram of the structure of a fixed-focus lens according to Embodiment 4 of this application is shown. Detailed Implementation

[0026] To better understand this application, various aspects of this application will be described in detail with reference to the accompanying drawings. It should be understood that these detailed descriptions are merely descriptions of exemplary embodiments of this application and are not intended to limit the scope of this application in any way.

[0027] In the accompanying drawings, the thickness, size, and shape of the lenses have been slightly exaggerated for ease of illustration. Specifically, the shapes of the spherical or aspherical surfaces shown in the drawings are illustrated by way of example. That is, the shapes of the spherical or aspherical surfaces are not limited to those shown in the drawings. The drawings are for illustrative purposes only and are not drawn strictly to scale.

[0028] In this article, the paraxial region refers to the region near the optical axis. If the lens surface is convex and the location of the convexity is not defined, it means that the lens surface is convex at least in the paraxial region; if the lens surface is concave and the location of the concaveness is not defined, it means that the lens surface is concave at least in the paraxial region. The surface of each lens closest to the subject is called the object-side surface of the lens, and the surface of each lens closest to the imaging plane is called the image-side surface of the lens.

[0029] It should also be understood that the terms "comprising," "including," "having," "containing," and / or "comprises" as used in this specification indicate the presence of the stated features, elements, and / or components, but do not exclude the presence or addition of one or more other features, elements, components, and / or combinations thereof. It should be noted that in this specification, the expressions "first," "second," "third," etc., are used only to distinguish one feature from another and do not imply any limitation on the features.

[0030] Unless otherwise specified, all terms used herein shall have the same meaning as commonly understood by one of ordinary skill in the art to which this application pertains. Terms shall be interpreted as having the meaning consistent with their meaning in the context of the relevant art and shall not be interpreted in an idealized or overly formal sense unless expressly stated herein.

[0031] It should be noted that, unless otherwise specified, the embodiments and features described in this application can be combined with each other. This application will now be described in detail with reference to the accompanying drawings and embodiments.

[0032] A fixed-focus lens according to an exemplary embodiment of this application may include a first lens, a second lens, a third lens, a fourth lens, a fifth lens, a sixth lens, and a seventh lens, and these seven lenses are arranged sequentially along the optical axis from the object side to the image plane. An air gap may exist between any two adjacent lenses among the first to seventh lenses.

[0033] In an exemplary embodiment, the first lens may have negative optical power. The object-side surface of the first lens may be concave, and the image-side surface may also be concave. By configuring the first lens with the above-described structure, light rays with a large field of view can be converged into the system as much as possible, which is beneficial for improving the field of view of the fixed-focus lens. The maximum field of view of the fixed-focus lens may be greater than or equal to 116°.

[0034] In an exemplary embodiment, the second lens may have negative optical power. The object-side surface of the second lens may be convex, and the image-side surface may be concave. By configuring the second lens with the above-described structure, the direction of light can be effectively controlled, the system aberrations of the fixed-focus lens can be reduced, and the image quality of the fixed-focus lens can be improved.

[0035] In an exemplary embodiment, the third lens may have positive optical power. The object-side surface of the third lens may be convex, and the image-side surface may also be convex. By configuring the third lens with the above-described structure, the exit pupil diameter when light enters the aperture stop position can be effectively controlled, which helps to reduce the overall aperture of the system and decrease the total optical length of the fixed-focus lens.

[0036] In an exemplary embodiment, the fourth lens may have positive optical power. The object-side surface of the fourth lens may be convex, and the image-side surface may also be convex. By configuring the fourth lens with the above-described structure, chromatic aberration caused by light emitted through the aperture can be effectively reduced, thereby improving the image quality of the fixed-focus lens.

[0037] In an exemplary embodiment, the fifth lens may have negative optical power. The object-side surface of the fifth lens may be concave, and the image-side surface may also be concave. Designing the fifth lens as a negative lens, in combination with the fourth and sixth lenses which have positive optical power, allows for a more compact structure of the fixed-focus lens, facilitating miniaturization of the fixed-focus lens and improving the correction of system aberrations.

[0038] In an exemplary embodiment, the sixth lens may have positive optical power. The object-side surface of the sixth lens may be convex, and the image-side surface may also be convex. Designing the sixth lens as a positive lens, and pairing it with the fifth lens having negative optical power, allows for a more compact structure of the fixed-focus lens, which is beneficial for miniaturizing the fixed-focus lens and for correcting system aberrations.

[0039] In an exemplary embodiment, the seventh lens may have positive optical power. The object-side surface of the seventh lens may be convex, and the image-side surface may be concave. By setting the seventh lens to the above-described structural form, the direction of light can be effectively controlled, allowing the light rays emitted from the sixth lens to transition smoothly to the imaging plane. This is beneficial for correcting some field curvature and astigmatism, and also helps to control the chief ray angle (CRA) of the fixed-focus lens, thereby improving the relative illumination of the fixed-focus lens.

[0040] In an exemplary embodiment, the fourth lens can be a glass lens. The first, second, third, fifth, sixth, and seventh lenses can be plastic lenses. Using a hybrid of glass and plastic lenses reduces the cost of the fixed-focus lens and balances its high and low temperature performance, ensuring good image quality without blurring within a temperature range of -40℃ to 80℃. Furthermore, using glass lenses helps correct chromatic aberration, improves color saturation, and facilitates confocal focusing of visible and infrared light.

[0041] In an exemplary embodiment, the fixed-focus lens may further include an aperture stop. The aperture stop is disposed between the first and second lenses, or between the second and third lenses, or between the third and fourth lenses. In other examples, when the aperture stop is disposed between the third and fourth lenses, it may be disposed on the image-side surface of the third lens or on the object-side surface of the fourth lens. By providing an aperture stop, the amount of light entering the system can be effectively reduced, the overall optical length of the fixed-focus lens can be shortened, and the maximum aperture of the front and rear lens groups can be reduced.

[0042] In an exemplary embodiment, the effective focal length F1 of the first lens, the effective focal length F2 of the second lens, and the effective focal length F3 of the third lens can satisfy: 0.60 ≤ (F2 + F3) / F1 ≤ 1.57. Reasonably allocating the optical power of the first, second, and third lenses can effectively control the light path, achieving a large aperture for the fixed-focus lens; simultaneously, it can reduce the overall aperture of the system, achieving miniaturization of the fixed-focus lens. The aperture number Fno of the fixed-focus lens can satisfy: Fno ≤ 1.29.

[0043] In an exemplary embodiment, the total optical length (TTL) and the back focal length (BFL) of a fixed-focus lens can satisfy the following ratio: 3.79 ≤ TTL / BFL ≤ 4.13. A reasonable configuration of the ratio of the total optical length to the back focal length of a fixed-focus lens enables the lens to have a long back focal length, which provides more assembly space for other optical components, facilitates the assembly of the fixed-focus lens, and improves the assembly yield.

[0044] In an exemplary embodiment, the combined focal length F123 of the first to third lenses and the axial distance d4567 from the object-side surface of the fourth lens to the image-side surface of the seventh lens can satisfy: -1.10 ≤ F123 / d4567 ≤ -0.83. By rationally configuring the ratio of the combined focal length of the first to third lenses to the axial distance from the object-side surface of the fourth lens to the image-side surface of the seventh lens, the individual lenses can have good manufacturability, reducing the sensitivity of the fixed-focus lens; simultaneously, it can also reduce the air gap between adjacent lenses, thereby reducing the overall optical length of the fixed-focus lens and achieving miniaturization. The total optical length (TTL) of the fixed-focus lens can satisfy: TTL ≤ 22.4 mm.

[0045] In an exemplary embodiment, the total optical length (TTL) and the total image height (H) of the fixed-focus lens can satisfy the following ratio: 3.07 ≤ TTL / H ≤ 3.56. By rationally configuring the ratio of the total optical length to the total image height of the fixed-focus lens, the total optical length can be constrained within a certain range given a fixed total image height, which is beneficial for achieving miniaturization of the fixed-focus lens.

[0046] In an exemplary embodiment, the effective focal length F4 of the fourth lens and the effective focal length F1 of the first lens can satisfy: -1.57 ≤ F4 / F1 ≤ -1.46. The fourth lens is a glass lens with a high Abbe number. By rationally configuring the ratio of the effective focal lengths of the fourth lens and the first lens, chromatic aberration caused when light passes through the aperture stop can be effectively corrected, which is beneficial to improving the color saturation of the fixed-focus lens, improving the imaging performance of the fixed-focus lens, and also beneficial to achieving confocal focusing of visible light and infrared light.

[0047] In an exemplary embodiment, the combined focal length F56 of the fifth and sixth lenses and the total effective focal length F of the fixed-focus lens can satisfy: 9.0 ≤ F56 / F ≤ 22.9. By rationally configuring the combined focal length of the fifth and sixth lenses, the temperature performance variations of the fixed-focus lens can be kept within the compensation capabilities of the lens's assembly process and available materials, ensuring that the optical performance of the fixed-focus lens remains focused within a temperature range of -40℃ to 80℃, thus achieving a heat-free fixed-focus lens.

[0048] In an exemplary embodiment, the combined focal length F56 of the fifth and sixth lenses and the effective focal length F4 of the fourth lens satisfy the following condition: 3.06 ≤ F56 / F4 ≤ 9.6. The fourth lens is a glass lens, which, when paired with the plastic fifth and sixth lenses, and with a carefully configured ratio of the combined focal length of the fifth and sixth lenses to the effective focal length of the fourth lens, ensures that the temperature performance variations of the fixed-focus lens remain within the compensation capabilities of the lens's assembly process and available materials. This guarantees that the optical performance of the fixed-focus lens remains focused within a temperature range of -40℃ to 80℃, achieving a heat-free fixed-focus lens.

[0049] In an exemplary embodiment, the radius of curvature R11 of the object-side surface of the first lens, the radius of curvature R12 of the image-side surface of the first lens, and the effective focal length F1 of the first lens can satisfy: 12.78 ≤ (R11 + R12) / F1 ≤ 48. By rationally configuring the ratio of the sum of the radii of curvature of the object-side and image-side surfaces of the first lens to the effective focal length of the first lens, light rays from different fields of view can be converged into the system, which is beneficial for improving the field of view of the fixed-focus lens. The maximum field of view (FOV) of the fixed-focus lens can satisfy: FOV ≥ 116°.

[0050] In an exemplary embodiment, the quadratic curvature coefficient K21 of the object-side surface of the second lens, the quadratic curvature coefficient K22 of the image-side surface of the second lens, and the effective focal length F2 of the second lens can satisfy: 0.04mm -1 ≤|(K21+K22) / F2|≤1.20mm -1 By properly configuring the ratio of the sum of the second curvature coefficients of the object-side and image-side surfaces of the second lens to the effective focal length of the second lens, the direction of light can be effectively controlled, various aberrations formed by light rays can be balanced, and the image quality of a fixed-focus lens can be improved.

[0051] In an exemplary embodiment, the combined focal length F567 of the fifth to seventh lenses and the effective focal length F1 of the first lens can satisfy: -2.37 ≤ F567 / F1 ≤ -1.90. Properly configuring the ratio of the combined focal length of the fifth to seventh lenses to the effective focal length of the first lens helps balance the aberrations of the fixed-focus lens and improve its resolving power.

[0052] In an exemplary embodiment, the effective focal length F7 of the seventh lens and the total effective focal length F of the fixed-focus lens can satisfy: 5.35≤F7 / F≤6.45. Properly configuring the effective focal length of the seventh lens can effectively control the direction of light, allowing the light rays emitted from the sixth lens to smoothly transition to the imaging plane. This is beneficial for correcting some field curvature and astigmatism, and also helps control the CRA angle of the fixed-focus lens, improving the relative illumination of the fixed-focus lens.

[0053] In an exemplary embodiment, the second curvature coefficient K71 of the object-side surface of the seventh lens, the second curvature coefficient K72 of the image-side surface of the seventh lens, and the effective focal length F7 of the seventh lens satisfy the following condition: 2.97mm. -1 ≤(K71+K72) / F7≤5.46mm -1 By properly configuring the ratio of the sum of the second curvature coefficients of the object-side and image-side surfaces of the seventh lens to the effective focal length of the seventh lens, the direction of light can be effectively controlled, allowing the light rays emitted from the sixth lens to smoothly transition to the imaging plane. This is beneficial for correcting some field curvature and astigmatism, and also helps control the CRA angle of the fixed-focus lens, thereby improving the relative illumination of the fixed-focus lens.

[0054] In an exemplary embodiment, the on-axis distance T1S from the first lens to the aperture stop and the total optical length TTL of the fixed-focus lens can satisfy: 0.15 ≤ T1S / TTL ≤ 0.41. By appropriately configuring the ratio of the on-axis distance from the first lens to the aperture stop to the total optical length of the fixed-focus lens, the aperture stop can be positioned appropriately, thereby effectively controlling the light path and improving the relative illumination of the fixed-focus lens while meeting the image size requirements.

[0055] In an exemplary embodiment, the maximum effective half-aperture SD71 of the object side of the seventh lens and the maximum effective half-aperture SD of the aperture stop are... sto It can satisfy: 1.06≤SD71 / SD sto ≤1.65. By properly configuring the ratio of the maximum effective half-aperture of the object side of the seventh lens to the maximum effective half-aperture of the aperture stop, the direction of light can be effectively controlled, thereby maximizing the light transmission of the fixed-focus lens while improving the image brightness behind the fixed-focus lens.

[0056] The fixed-focus lens according to the above embodiments of this application can employ multiple lenses, such as the seven lenses mentioned above. By rationally allocating optical parameters such as the optical power, surface shape, center thickness of each lens, and on-axis spacing between each lens, at least one of the following characteristics can be achieved in the fixed-focus lens: large aperture, miniaturization, low cost, high resolution, infrared confocality, and calorific value. The fixed-focus lens provided in this application has an 8M resolution and good infrared confocality, resulting in excellent infrared imaging performance at night, making it a dual-purpose imaging lens for both day and night use.

[0057] In embodiments of this application, at least one of the surfaces of the first to seventh lenses is an aspherical surface. An aspherical lens is characterized by a continuously changing curvature from its center to its periphery. Unlike a spherical lens, which has a constant curvature from its center to its periphery, an aspherical lens has superior curvature radius characteristics, offering advantages in improving distortion and astigmatism. By employing an aspherical lens, aberrations occurring during imaging can be eliminated as much as possible, thereby improving image quality.

[0058] Those skilled in the art should understand that the total optical length (TTL) of the fixed-focus lens used above refers to the axial distance from the object-side surface of the first lens to the imaging surface; and the back focal length (BFL) of the fixed-focus lens refers to the axial distance from the image-side surface of the seventh lens to the imaging surface.

[0059] However, those skilled in the art should understand that, without departing from the technical solutions claimed in this application, the number of lenses constituting a fixed-focus lens can be changed to obtain the various results and advantages described in this specification.

[0060] The following describes in further detail, with reference to the accompanying drawings, specific embodiments of a fixed-focus lens applicable to the above-described embodiments.

[0061] Example 1

[0062] The following is for reference Figure 1 A fixed-focus lens according to Embodiment 1 of this application is described. Figure 1 This is a schematic diagram of the fixed-focus lens according to Embodiment 1 of this application.

[0063] like Figure 1 As shown, the fixed-focus lens 100 includes, along the optical axis from the object side to the imaging plane IMG, a first lens L1, a second lens L2, a third lens L3, a fourth lens L4, a fifth lens L5, a sixth lens L6, and a seventh lens L7. The aperture stop STO can be positioned between the third lens L3 and the fourth lens L4.

[0064] The first lens L1 has negative optical power, and its object side S1 is concave, and its image side S2 is concave.

[0065] The second lens L2 has negative optical power, its object side S3 is convex, and its image side S4 is concave.

[0066] The third lens L3 has positive optical power, and its object side S5 is convex, while its image side S6 is convex.

[0067] The fourth lens L4 has positive optical power, and its object side S7 is convex, while its image side S8 is convex.

[0068] The fifth lens L5 has negative optical power, and its object side S9 is concave, and its image side S10 is concave.

[0069] The sixth lens L6 has positive optical power, and its object side S11 is convex, and its image side S12 is convex.

[0070] The seventh lens L7 has positive optical power, with its object side S13 being convex and its image side S14 being concave.

[0071] A filter CG may also be included between the seventh lens L7 and the imaging plane IMG. The filter CG has an object-side surface S15 and an image-side surface S16. Light from the object passes sequentially through each surface S1 to S16 and is finally imaged onto the imaging plane IMG. It should be noted that surfaces S1 to S16 are... Figure 1 Not shown in the image.

[0072] Table 1 shows the basic parameters of the fixed-focus lens 100 of Embodiment 1, where the units for radius of curvature, thickness / distance, and focal length are millimeters (mm). The aperture number Fno of the fixed-focus lens is 1.283. The maximum field of view (FOV) of the fixed-focus lens is 142.16°.

[0073]

[0074] Table 1

[0075] In this embodiment, the object-side surface and image-side surface of any one of the first lens L1 to the third lens L3 and the fifth lens L5 to the seventh lens L7 are aspherical. The surface shape x of each aspherical lens can be defined using, but is not limited to, the following aspherical formula:

[0076]

[0077] Where x is the distance vector from the vertex of the aspherical surface at a height of h along the optical axis; c is the paraxial curvature of the aspherical surface, c = 1 / R (i.e., the paraxial curvature c is the reciprocal of the radius of curvature R in Table 1 above); k is the conic coefficient; Ai is the i-th order correction coefficient of the aspherical surface. Table 2 gives the conic coefficient k and higher-order coefficients A4, A6, A8, A14 that can be used for the aspherical surfaces S1-S6, S9-S14 in Example 1. 10 A12 A 14 and A 16 The conic coefficient k is the quadratic curvature coefficient mentioned above.

[0078] Face number K A4 A6 A8 A10 A12 A14 A16 S1 512.56 8.79E-04 -4.39E-05 8.83E-07 6.37E-09 -4.81E-10 5.50E-12 1.72E-14 S2 -0.69 3.30E-03 3.25E-04 -2.96E-05 1.23E-05 1.20E-06 -5.48E-07 4.41E-08 S3 12.71 -1.84E-02 2.73E-04 1.18E-04 -1.38E-05 -9.78E-07 2.54E-07 -1.63E-08 S4 -2.37 -1.37E-02 6.82E-04 -3.85E-05 -2.58E-06 1.67E-06 -2.53E-07 1.28E-08 S5 14.71 7.30E-03 -6.37E-04 -1.60E-05 8.95E-06 3.17E-07 -1.97E-07 1.20E-08 S6 -0.26 4.84E-03 1.37E-04 2.16E-05 -7.73E-10 -2.31E-07 -1.11E-08 1.39E-09 S9 4.03 -3.94E-03 3.48E-04 -5.75E-05 1.71E-06 3.42E-07 -4.58E-08 1.51E-09 S10 -5.47 -2.56E-03 6.46E-05 6.40E-06 -5.82E-07 2.97E-09 1.26E-08 -2.40E-09 S11 -7.71 -5.79E-05 -1.97E-04 3.94E-05 -1.75E-06 -7.02E-08 1.91E-08 -1.80E-09 S12 -5.17 -4.72E-03 3.06E-04 -1.84E-05 1.01E-08 1.30E-07 -8.31E-09 7.20E-10 S13 -0.34 -1.48E-03 -1.12E-04 2.56E-07 -9.05E-07 5.17E-10 9.74E-09 5.02E-11 S14 96.09 -3.41E-03 1.20E-04 -1.99E-05 -6.53E-08 1.18E-07 -6.91E-09 3.98E-10

[0079] Table 2

[0080] Example 2

[0081] The following is for reference Figure 2 Describes a fixed-focus lens according to Embodiment 2 of this application. Figure 2 This is a schematic diagram of the fixed-focus lens according to Embodiment 2 of this application.

[0082] like Figure 2 As shown, the fixed-focus lens 200 includes, along the optical axis from the object side to the imaging plane IMG, a first lens L1, a second lens L2, a third lens L3, a fourth lens L4, a fifth lens L5, a sixth lens L6, and a seventh lens L7. The aperture stop STO can be positioned between the second lens L2 and the third lens L3.

[0083] The first lens L1 has negative optical power, and its object side S1 is concave, and its image side S2 is concave.

[0084] The second lens L2 has negative optical power, its object side S3 is convex, and its image side S4 is concave.

[0085] The third lens L3 has positive optical power, and its object side S5 is convex, while its image side S6 is convex.

[0086] The fourth lens L4 has positive optical power, and its object side S7 is convex, while its image side S8 is convex.

[0087] The fifth lens L5 has negative optical power, and its object side S9 is concave, and its image side S10 is concave.

[0088] The sixth lens L6 has positive optical power, and its object side S11 is convex, and its image side S12 is convex.

[0089] The seventh lens L7 has positive optical power, with its object side S13 being convex and its image side S14 being concave.

[0090] A filter CG may also be included between the seventh lens L7 and the imaging plane IMG. The filter CG has an object-side surface S15 and an image-side surface S16. Light from the object passes sequentially through each surface S1 to S16 and is finally imaged onto the imaging plane IMG. It should be noted that surfaces S1 to S16 are... Figure 2 Not shown in the image.

[0091] Table 3 shows the basic parameters of the fixed-focus lens 200 of Embodiment 2, where the units for radius of curvature, thickness / distance, and focal length are millimeters (mm). The aperture number Fno of the fixed-focus lens is 1.285. The maximum field of view (FOV) of the fixed-focus lens is 129.8°.

[0092]

[0093] Table 3

[0094] In this embodiment, the object-side surface and image-side surface of any one of the lenses L1, L2, L4 to L7 are aspherical. Table 4 shows the conic coefficient k and higher-order coefficients A4, A6, A8, and A6 that can be used for the aspherical surfaces S1-S4 and S7-S14 in Embodiment 2. 10 A 12 A 14 and A 16 .

[0095] Face number K A4 A6 A8 A10 A12 A14 A16 S1 361.59 1.29E-03 -5.08E-05 6.05E-07 9.86E-09 -3.22E-10 1.33E-11 -1.95E-13 S2 -1.13 6.66E-03 3.65E-04 9.56E-06 1.35E-05 3.14E-08 -4.64E-07 4.79E-08 S3 1.66 -1.94E-02 3.99E-04 9.86E-05 -9.70E-06 -1.01E-06 1.77E-07 -1.27E-08 S4 -2.18 -1.49E-02 6.91E-04 -5.08E-05 6.79E-09 1.68E-06 -3.00E-07 1.62E-08 S7 37.91 7.22E-03 -6.63E-04 -1.45E-05 7.91E-06 3.02E-07 -1.68E-07 9.50E-09 S8 -0.47 4.51E-03 1.39E-04 2.26E-05 2.97E-07 -2.83E-07 -1.62E-08 2.09E-09 S9 6.46 -4.47E-03 3.49E-04 -4.38E-05 9.14E-07 2.01E-07 -2.80E-08 1.42E-09 S10 -5.48 -1.63E-03 6.49E-05 6.97E-06 -1.15E-06 -6.75E-08 5.78E-09 -9.24E-11 S11 -8.07 6.97E-04 -1.53E-04 3.62E-05 -2.84E-06 -1.41E-07 2.41E-08 -8.38E-10 S12 -5.46 -4.29E-03 3.18E-04 -1.78E-05 -6.04E-07 1.24E-07 1.31E-10 -2.38E-10 S13 0.66 -1.37E-04 -2.45E-05 -2.05E-06 -4.87E-07 -9.69E-09 1.55E-09 -9.93E-12 S14 61.58 -2.69E-03 2.54E-04 -1.42E-05 -8.18E-07 6.12E-08 -6.86E-10 -1.69E-11

[0096] Table 4

[0097] Example 3

[0098] The following is for reference Figure 3 Describes a fixed-focus lens according to Embodiment 3 of this application. Figure 3 This is a schematic diagram of the fixed-focus lens according to Embodiment 3 of this application.

[0099] like Figure 3 As shown, the fixed-focus lens 300 includes, along the optical axis from the object side to the imaging plane IMG, a first lens L1, a second lens L2, a third lens L3, a fourth lens L4, a fifth lens L5, a sixth lens L6, and a seventh lens L7. The aperture stop STO can be set on the image side of the third lens L3.

[0100] The first lens L1 has negative optical power, and its object side S1 is concave, and its image side S2 is concave.

[0101] The second lens L2 has negative optical power, its object side S3 is convex, and its image side S4 is concave.

[0102] The third lens L3 has positive optical power, and its object side S5 is convex, while its image side S6 is convex.

[0103] The fourth lens L4 has positive optical power, and its object side S7 is convex, while its image side S8 is convex.

[0104] The fifth lens L5 has negative optical power, and its object side S9 is concave, and its image side S10 is concave.

[0105] The sixth lens L6 has positive optical power, and its object side S11 is convex, and its image side S12 is convex.

[0106] The seventh lens L7 has positive optical power, with its object side S13 being convex and its image side S14 being concave.

[0107] A filter CG may also be included between the seventh lens L7 and the imaging plane IMG. The filter CG has an object-side surface S15 and an image-side surface S16. Light from the object passes sequentially through each surface S1 to S16 and is finally imaged onto the imaging plane IMG. It should be noted that surfaces S1 to S16 are... Figure 3 Not shown in the image.

[0108] Table 5 shows the basic parameters of the fixed-focus lens 300 of Embodiment 3, where the units for radius of curvature, thickness / distance, and focal length are millimeters (mm). The aperture number Fno of the fixed-focus lens is 1.287. The maximum field of view (FOV) of the fixed-focus lens is 145.56°.

[0109]

[0110] Table 5

[0111] In this embodiment, the object-side surface and image-side surface of any one of the lenses L1 to L3 and L5 to L7 are aspherical surfaces. Table 6 shows the conic coefficient k and higher-order coefficients A4, A6, A8, and A6 that can be used for the aspherical surfaces S1-S6 and S9-S14 in Embodiment 3. 10 A 12 A 14 and A 16 .

[0112]

[0113]

[0114] Table 6

[0115] Example 4

[0116] The following is for reference Figure 4 A fixed-focus lens according to Embodiment 4 of this application is described. Figure 4 This is a schematic diagram of the fixed-focus lens according to Embodiment 4 of this application.

[0117] like Figure 4As shown, the fixed-focus lens 400 includes, along the optical axis from the object side to the imaging plane IMG, a first lens L1, a second lens L2, a third lens L3, a fourth lens L4, a fifth lens L5, a sixth lens L6, and a seventh lens L7. The aperture stop STO can be positioned between the first lens L1 and the second lens L2.

[0118] The first lens L1 has negative optical power, and its object side S1 is concave, and its image side S2 is concave.

[0119] The second lens L2 has negative optical power, its object side S3 is convex, and its image side S4 is concave.

[0120] The third lens L3 has positive optical power, and its object side S5 is convex, while its image side S6 is convex.

[0121] The fourth lens L4 has positive optical power, and its object side S7 is convex, while its image side S8 is convex.

[0122] The fifth lens L5 has negative optical power, and its object side S9 is concave, and its image side S10 is concave.

[0123] The sixth lens L6 has positive optical power, and its object side S11 is convex, and its image side S12 is convex.

[0124] The seventh lens L7 has positive optical power, with its object side S13 being convex and its image side S14 being concave.

[0125] A filter CG may also be included between the seventh lens L7 and the imaging plane IMG. The filter CG has an object-side surface S15 and an image-side surface S16. Light from the object passes sequentially through each surface S1 to S16 and is finally imaged onto the imaging plane IMG. It should be noted that surfaces S1 to S16 are... Figure 4 Not shown in the image.

[0126] Table 7 shows the basic parameters of the fixed-focus lens 400 of Embodiment 4, where the units for radius of curvature, thickness / distance, and focal length are millimeters (mm). The aperture number Fno of the fixed-focus lens is 1.285. The maximum field of view (FOV) of the fixed-focus lens is 116.46°.

[0127]

[0128]

[0129] Table 7

[0130] In this embodiment, the object-side surface and image-side surface of any one of the lenses L1 to L3 and L5 to L7 are aspherical. Table 8 shows the conic coefficient k and higher-order coefficients A4, A6, A8, and A6 that can be used for the aspherical surfaces S1-S6 and S9-S14 in Embodiment 4. 10 A 12 A 14 and A 16 .

[0131] Face number K A4 A6 A8 A10 A12 A14 A16 S1 204.16 1.43E-03 -5.72E-05 7.33E-08 4.06E-08 -2.75E-10 -2.09E-11 3.62E-13 S2 -0.29 3.24E-04 -1.86E-04 7.05E-05 -5.90E-06 -1.50E-06 2.09E-07 -1.26E-08 S3 -6.51 -2.08E-02 9.43E-04 1.21E-04 -1.49E-05 -1.82E-06 4.16E-07 -2.61E-08 S4 -3.71 -1.40E-02 1.08E-03 -6.50E-05 -3.17E-06 1.81E-06 -2.64E-07 1.33E-08 S5 34.03 7.81E-03 -6.80E-04 -7.13E-06 7.93E-06 2.41E-07 -1.82E-07 1.16E-08 S6 -0.40 4.86E-03 2.23E-04 1.89E-05 -7.10E-07 -2.60E-07 -1.59E-10 1.67E-09 S9 7.26 -3.96E-03 3.54E-04 -3.96E-05 6.36E-07 2.14E-07 -1.90E-08 8.96E-10 S10 -4.43 -1.66E-03 7.41E-05 6.16E-06 -8.11E-07 -3.07E-08 7.27E-09 -7.22E-10 S11 -5.89 1.24E-03 -2.60E-04 3.77E-05 -2.26E-06 -8.97E-08 2.37E-08 -1.39E-09 S12 -5.96 -4.51E-03 3.34E-04 -1.99E-05 -5.91E-07 1.38E-07 5.56E-10 -2.38E-10 S13 0.04 -8.03E-04 -8.29E-05 -2.44E-06 -2.48E-07 -1.83E-08 4.63E-09 -3.28E-11 S14 82.41 -3.46E-03 2.31E-04 -1.81E-05 -7.92E-07 1.04E-07 -1.04E-09 -4.91E-11

[0132] Table 8

[0133] In summary, the conditional expressions in Examples 1 to 4 satisfy the relationships shown in Table 9.

[0134] Conditional / Example 1 2 3 4 (F2+F3) / F1 0.848 0.811 1.438 0.888 TTL / BFL 3.892 3.846 4.081 4.023 F123 / d4567 -1.055 -0.869 -1.022 -0.903 TTL / H 3.179 3.147 3.338 3.494 F4 / F1 -1.497 -1.481 -1.553 -1.534 F56 / F 15.437 12.456 20.683 11.026 F56 / F4 6.498 5.501 8.704 4.587 (R11+R12) / F1 42.703 42.020 28.505 17.847 <![CDATA[|(K21+K22) / F2|(mm -1 )]]> 0.878 0.044 0.193 0.851 F567 / F1 -2.299 -2.190 -2.279 -2.140 F7 / F 6.127 5.874 5.515 6.296 <![CDATA[(K71+K72) / F7(mm -1 )]]> 5.107 3.332 4.722 4.265 T1S / TTL 0.374 0.258 0.354 0.192 <![CDATA[SD71 / SD sto ]]> 1.149 1.267 1.266 1.567

[0135] Table 9

[0136] This application also provides an imaging device, wherein the electronic photosensitive element may be a photocoupled device (CCD) or a complementary metal oxide semiconductor device (CMOS), and the imaging device is equipped with the fixed-focus lens described above.

[0137] The above description is merely a preferred embodiment of this application and an explanation of the technical principles employed. Those skilled in the art should understand that the scope of the invention involved in this application is not limited to technical solutions formed by specific combinations of the above-described technical features, but should also cover other technical solutions formed by arbitrary combinations of the above-described technical features or their equivalents without departing from the inventive concept. For example, technical solutions formed by substituting the above features with (but not limited to) technical features with similar functions disclosed in this application.

Claims

1. A fixed-focus lens, characterized in that, Along the optical axis from the object side to the image plane, the sequence includes: A first lens with negative optical power; A second lens with negative optical power; A third lens with positive optical power; A fourth lens with positive optical power; A fifth lens with negative optical power; A sixth lens with positive optical power; and A seventh lens with positive optical power; Wherein, the effective focal length F1 of the first lens, the effective focal length F2 of the second lens, and the effective focal length F3 of the third lens satisfy: 0.60≤(F2+F3) / F1≤1.57; The combined focal length F56 of the fifth and sixth lenses and the effective focal length F4 of the fourth lens satisfy the following condition: 3.06 ≤ F56 / F4 ≤ 9.6; The fixed-focus lens has seven lenses with optical power.

2. The fixed-focus lens according to claim 1, characterized in that, The object-side surface of the first lens is concave, and the image-side surface is also concave. The object-side surface of the second lens is convex, and the image-side surface is concave. The object-side surface of the third lens is convex, and the image-side surface is also convex. The object-side surface of the fourth lens is convex, and the image-side surface is also convex. The object-side surface of the fifth lens is concave, and the image-side surface is also concave. The object-side surface of the sixth lens is convex, and the image-side surface is also convex; and The object-side surface of the seventh lens is convex, and the image-side surface is concave.

3. The fixed-focus lens according to claim 1 or 2, characterized in that, The total optical length (TTL) and the back focal length (BFL) of the fixed-focus lens satisfy the following condition: 3.79 ≤ TTL / BFL ≤ 4.

13.

4. The fixed-focus lens according to claim 1 or 2, characterized in that, The combined focal length F123 of the first lens to the third lens and the on-axis distance d4567 from the object side of the fourth lens to the image side of the seventh lens satisfy the following condition: -1.10≤F123 / d4567≤-0.

83.

5. The fixed-focus lens according to claim 1 or 2, characterized in that, The total optical length (TTL) of the fixed-focus lens and the holographic height (H) of the fixed-focus lens satisfy the following condition: 3.07 ≤ TTL / H ≤ 3.

56.

6. The fixed-focus lens according to claim 1 or 2, characterized in that, The effective focal length F4 of the fourth lens and the effective focal length F1 of the first lens satisfy the following condition: -1.57≤F4 / F1≤-1.

46.

7. The fixed-focus lens according to claim 1 or 2, characterized in that, The combined focal length F56 of the fifth lens and the sixth lens satisfies the following condition with respect to the total effective focal length F of the fixed-focus lens: 9.0 ≤ F56 / F ≤ 22.

9.

8. The fixed-focus lens according to claim 1 or 2, characterized in that, The radius of curvature R11 of the object side of the first lens, the radius of curvature R12 of the image side of the first lens, and the effective focal length F1 of the first lens satisfy: 12.78≤(R11+R12) / F1≤48.

9. The fixed-focus lens according to claim 1 or 2, characterized in that, The second lens's object-side curvature coefficient K21, the second lens's image-side curvature coefficient K22, and the second lens's effective focal length F2 satisfy the following condition: 0.04 mm. -1 ≤|(K21+K22) / F2|≤1.20mm -1 .

10. The fixed-focus lens according to claim 1 or 2, characterized in that, The combined focal length F567 of the fifth to seventh lenses and the effective focal length F1 of the first lens satisfy the following condition: -2.37≤F567 / F1≤-1.

90.

11. The fixed-focus lens according to claim 1 or 2, characterized in that, The effective focal length F7 of the seventh lens and the total effective focal length F of the fixed-focus lens satisfy the following condition: 5.35≤F7 / F≤6.

45.

12. The fixed-focus lens according to claim 1 or 2, characterized in that, The curvature coefficient K71 of the object-side surface of the seventh lens, the curvature coefficient K72 of the image-side surface of the seventh lens, and the effective focal length F7 of the seventh lens satisfy the following condition: 2.97mm. -1 ≤(K71+K72) / F7≤5.46mm -1 .

13. The fixed-focus lens according to claim 1 or 2, characterized in that, The fixed-focus lens also includes an aperture stop, and the on-axis distance T1S from the first lens to the aperture stop and the total optical length TTL of the fixed-focus lens satisfy the following condition: 0.15≤T1S / TTL≤0.

41.

14. The fixed-focus lens according to claim 1 or 2, characterized in that, The fixed-focus lens also includes an aperture stop, and the maximum effective half-diameter SD71 of the object-side surface of the seventh lens is equal to the maximum effective half-diameter SD of the aperture stop. sto Satisfies: 1.06 ≤ SD71 / SD sto ≤1.

65.

15. The fixed-focus lens according to claim 1, characterized in that, The fixed-focus lens satisfies any one of the following conditions: 0.811≤(F2+F3) / F1≤1.438 3.846≤TTL / BFL≤4.081 -1.055≤F123 / d4567≤-0.869, 3.147≤TTL / H≤3.494, -1.553≤F4 / F1≤-1.481, 11.026≤F56 / F≤20.683, 4.587≤F56 / F4≤8.704, 17.847≤(R11+R12) / F1≤42.703, 0.044mm -1 ≤|(K21+K22) / F2|≤0.878mm -1 , -2.299≤F567 / F1≤-2.140, 5.515≤F7 / F≤6.296, 3.332mm -1 ≤(K71+K72) / F7≤5.107mm -1 , 0.192≤T1S / TTL≤0.374, 1.149≤SD71 / SD sto ≤1.567, Wherein, F1 is the effective focal length of the first lens, F2 is the effective focal length of the second lens, F3 is the effective focal length of the third lens, TTL is the total optical length of the fixed-focus lens, BFL is the back focal length of the fixed-focus lens, F123 is the combined focal length of the first lens to the third lens, d4567 is the axial distance from the object side of the fourth lens to the image side of the seventh lens, H is the full image height of the fixed-focus lens, F4 is the effective focal length of the fourth lens, F56 is the combined focal length of the fifth and sixth lenses, F is the total effective focal length of the fixed-focus lens, and R11 is the object length of the first lens. The radius of curvature of the side surface, R12 is the radius of curvature of the image side surface of the first lens, K21 is the second curvature coefficient of the object side surface of the second lens, K22 is the second curvature coefficient of the image side surface of the second lens, F567 is the combined focal length of the fifth lens to the seventh lens, F7 is the effective focal length of the seventh lens, K71 is the second curvature coefficient of the object side surface of the seventh lens, K72 is the second curvature coefficient of the image side surface of the seventh lens, the fixed-focus lens also includes an aperture stop, T1S is the axial distance from the first lens to the aperture stop, SD71 is the maximum effective half-aperture of the object side surface of the seventh lens, SD sto This is the maximum effective half-aperture of the aperture.

Images